Yeah but besides the sanitation system,the aqueduct, the roads, the irrigation system, medicine,oratory, law, historians, dramatists,Vitruvius..what did those lousy Romans have?
2. Chemical warfare was used before the Romans, for instance, like that condiment, the greeks had it before them. (Though I don't believe the greeks invented it first either). For example, see this wikipedia article (which is really in need of some improvement) https://en.wikipedia.org/wiki/Timeline_of_chemical_warfare